Balzer, Jeffrey R, PhD

Crammond, Donald J, PhD

Meinert, Justin W, BPhil

Saca, Eyad E, MD

Thirumala, Parthatharasy D, MD

English

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Intraoperative Changes in Somatosensory Evoked Potentials as a Predictor of Perioperative Stroke in Carotid EndarterectomyJustin W. Meinert BPhil1, Eyad E. Saca MD2, Jeffrey R. Balzer PhD2, Donald J. Crammond PhD2, Parthasarathy D. Thirumala MD, MS21Drexel College of Medicine2University of Pittsburgh Medical Center Center for Clinical NeurophysiologyINTRODUCTIONPerioperative stroke is a known but severe neurological complication that can occur after carotid endarterectomy (CEA). Intraoperative neurophysiological monitoring with somatosensory evoked potentials (SSEPs) is utilized to warn the surgical team of potential ischemic changes. Current alarm criteria are an amplitude decrease of at least 50% or a latency increase of 10% or more.OBJECTIVESTo assess the usefulness of intraoperative changes in cortical SSEPs in predicting perioperative strokes during CEA.METHODSThis was a retrospective cohort study identifying all perioperative strokes that occurred at UPMC between 2010-2015. We defined perioperative stroke as all new onset neurological deficits occurring within the hospital stay and up to 30 days following the procedure. We further classified into major and minor strokes based on the presence of life altering deficits. Baseline amplitudes and latencies of cortical SSEPs were measured at pre-incision, incision, heparin administration, and pre-clamp. Comparison time points were measured at consistent time intervals post-clamp and post-closure.Figure #1: Classic example typical of SSEPRESULTSThere was a significant difference in mean amplitude change between controls and strokes at all time points after pre-incision, not including the end of the surgery. Patients with perioperative strokes had a significant intraoperative decrease in amplitude from all four baselines. An amplitude decrease of 50% or more was predictive of all strokes and major strokes alone from all four baselines. Receiver-Operator Characteristic (ROC) curve analysis identified changes from the pre-incision timepoint as the most reliable baseline for predicting stroke with an optimal cutoff of 55%.CONCLUSIONSA representative pre-incision time point should be used as baseline during CEA. Latency changes were very specific but are virtually insensitive, and do not appear to be very useful. The current alarm criteria of 50% decrease predicts stroke meaning it is inadequate as an alarm. Further studies should look at an an appropriate alarm criteria to prevent stroke.Figure #2: Receiver-Operator Characteristic curve analysis of % change from proposed amplitude and latency baselinesTable #1: Area under the curve, sensitivity and specificity of SSEPs in predicting stroke from each baselineFigure #3:  Density plots comparing mean % change from baseline in controls vs strokesPresenter Contact Information:Justin Meinert, MS4Drexel College of MedicinePhone: 724-814-1351Email: jwm323@drexel.eduSignificant Change Modality Optimal Cutoff (%) AUC 95% CI: Sensitivity SpecificityMajor stroke amplitude changes as a predictorPre-incision 55% 0.829 0.747-0.911 0.846 0.693Incision 50% 0.804 0.698-0.911 0.846 0.683Heparin 38% 0.744 0.621-0.866 0.731 0.663Pre-clamp 38% 0.744 0.619-0.868 0.808 0.653Major stroke latency changes as a predictorPre-incision 3.9% 0.649 0.527-0.770 0.500 0.772Incision 3.9% 0.591 0.460-0.721 0.462 0.782Heparin 2.5% 0.523 0.396-0.650 0.577 0.554Pre-clamp 2.1% 0.585 0.466-0.703 0.769 0.505Figure #4:  % change from baseline at each measured time point in controls vs strokes1. ACNS: Guidline 11B: Recommended Standards for Intraoperative Monitoring of Somatosensory Evoked Potentials. Am Clin Neurophysiology Soc Guide l:1–10, 20092. Brott TG, Howard G, Roubin GS, Meschia JF, Mackey A, Brooks W, et al: Long-Term Results of Stenting versus Endarterectomy for Carotid-Artery Stenosis. N Engl J Med 374:1021–1031, 2016 Available: http://www.nejm.org/doi/abs/10.1056/NEJMoa1505215.3. Caplan LR, Hennerici M: Impaired clearance of emboli (washout) is an important link between hypoperfusion, embolism, and ischemic stroke. Arch Neurol 55:1475–1482, 19984. DeLong ER, DeLong DM, Clarke-Pearson DL: Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics 44:837–45, 1988 Available: http://www.ncbi.nlm.nih.gov/pubmed/3203132.5. Domenick Sridharan N, Chaer RA, Thirumala PD, Balzer J, Long B, Tzeng E, et al: Somatosensory Evoked Potentials and Electroencephalography during Carotid Endarterectomy Predict Late Stroke but not Death, in Annals of Vascular Surgery38:105–112, 2017 6. Intemodino Group: Random Number Generator. Available: http://www.randomnumbergenerator.intemodino.com/en/.REFERENCES: (for full list please contact presenter)

Intraoperative Changes in Somatosensory Evoked Potentials as a Predictor of Perioperative Stroke in Carotid Endarterectomy

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Intraoperative Changes in Somatosensory Evoked Potentials as a Predictor of Perioperative Stroke in Carotid Endarterectomy

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